Golf training device



March 4, 1958 L. W. ALVAREZ GOLF TRAINING DEVICE Filed Nov. 2, 1953 "Pl/l. SE 0N CONDUG TOR 79 PULSE o/v CONDUCTOR 79 VOLTA 65 AT (FAST SWING 1 VOL TA 65 A 0505s conmf/vstk //9 2 Sheets-Sheet l KPULSE 0N CONDUCTOR 79 PULSE 0N CONDUCTOR 79' vol. TA 65 AT POI/VT I05 )7 VOLTAGE I CONDE/VS (SLOW SWING ATTORNEYS INVENTOR. LUIS w. ALVA REZ L. w. ALVAREZ GOLF TRAINING DEVICE March 4, 1958 INVENTOR. LUIS w. ALVAREZ 2 Sheets-Sheet 2 ATTORNEYS United States Patent "Q GOLF TRAINING DEVICE Luis W. Alvarez, Berkeley, Calif., assignor to and Company, San Francisco, Calif., a partnership Application November 2, 1953, Serial No. 389,586

9 Claims. (Cl. 273-186) This invention is directed to golf training devices. The principal purpose of a device of such character is to enable the golfer to check visually on his swing with respect to the line of club movement relative to the ball to be impacted and also with respect to the velocity of club head motion as the ball is impacted. Information of such conditions make instantly available, in a training device, knowledge of the flight path and distance to he travelled by a golf ball if the golfers swing in play could be made to coincide with that exhibited in practice.

In a preferred embodiment of the invention, as it will be described herein, apparatus is provided whereby the golfer, as he swings the club head to contact a ball, either real or simulated, is able to observe a series of images of the club head, as if arrested, in various positions as it is moving along the path of swing to the ball and during at least a part of the follow-through. By such an arrangement it is possible for the golfer to observe during the course of the swing the club head position as it approaches and leaves the position whereat the ball would be contacted. In this way direct observation may be made during the course of the golfers normal swing of the club head without any lifting of the head which would tend to defeat a so-called good swing. In fact, use of the device encourages keeping the head down so that observations can be made. Such observations make it possible to determine whether the club face, at the instant of impact, happens to be normal to the intended direction that the ball shall take in flight or is held in an open or closed position. It is also possible to determine, by the invention herein to be set forth, whether the golf ball actually would be contacted at the center of the club head face or at the heel (shank) or toe thereof. In addition, direct observation during the course of the swing may be made of the precise path of the club head movement relative to an optimum swing line and concurrently with this there may be had an indication of the club head velocity in the region of impact with the ball.

As the invention is constituted, the ball, which is to be the target toward which the golfer is swinging the club, may be either real or simulated. If simulated the bail may be exemplified by an image of a ball at the desired impact point or it may be another appropriate form of indication toward which the club head is swung. As a guide to determine the optimum swing path along which the club head is to move an appropriate strip may be positioned to indicate both the desired optimum line of swing and the line of ball flight. A series of light-sensitive phototubes is positioned in the region of ball contact to extend both along and parallel and adjacent to the swing path in the region of ball impact. The phototubes are preferably illuminated during the course of the operation of the trainer device in such a way that the continuous illumination is interrupted at the instant the club head moves through the light path between the source and the phototube.

According to one form of operation, the interruption of light upon each successive phototube by the golf club "ice moving through the successive light beams causes a trigger pulse to be developed by an appropriate pulsing circuit therewith associated. The developed pulse causes a lamp (generally known as a "stroboscopic lamp) associated with the phototube to flash. Thus, as a club head is swung in front of the several phototubes the lamps are flashed in succession. The brilliance of the flashing lamps is sufiicient to illuminate the club head and to produce a series of positionally arrested images thereof while the club head is in its lowest position of arc of swing, generally corresponding to its ball impact region toward which the golfers eyes are directed at all times during the swing. The flashing illumination of the relatively intense light sources illuminating the club head is adequate to create for each flash an arrested position image of the instantaneous club head position, which is seen by direct observation.

The controlling of the flashing of the lamps to produce light along the swing path may in one form of the operation be accompanied by an initiation into operation of a timing circuit which, through appropriate circuit arrangements, is caused to indicate on a suitable meter the elapsed time interval during which the club head, as swung, is moved between two selected points of measurement. These points, for instance, may be a point relatively close to that at which the club head is adapted actually to meet the ball in the striking operation and a selected point immediately ahead of such contact point. With such a form of control and with the distance known between the two points of observation, as well as the club weight and ball weight, it is possible, by calibrating an indicating device in terms of a struck golf ball to obtain a reading or indication exemplifying the distance to which a golf ball would be expected to be moved as a result of the particular impact velocity of the striking club head, assuming, of course, still air and standard temperature and barometric pressure, and also a standard grass of standard wetness.

In the operation, as it will be herein set forth, the posi-' tion of the club head in its motion toward the ball is estab-' lished without regard to time so that instantly the observer may determine the way in which the ball has been contacted.

With these thoughts in mind it will be apparent that the observer or player can determine immediately and for himself whether the club head is actually traveling in a direction normal to the desired direction of flight which should be taken by the impacted ball so that a decision can be reached at once as to whether the ball would actually adopt an optimum flight path, or by direct observation, whether the ball would be sliced or hooked, depending upon whether the golfer caused the club head to contact the ball from a direction leading from a point outside the normal swing path to the ball or from a point inside the normal swing path to the ball. These observations thus give a good idea of the actual movement of the club head in a vertical plane. Movement in the horizontal plane is,

of course, readily observable by equally as precise observation, in which case it is possible to determine whether the ball would have been topped or, as the golfer says, hit fat or, and preferably, hit squarely.

With these thoughts in mind it becomes an object of this invention to provide a golf training device in which it is possible, first, to observe the precise line of club head movement toward a ball concurrently with the swinging motion of the club head and, in addition, to provide ways and means by which visual observation may be used to establish the impact point on the club head at which the club head actually strikes the ball to be moved. An additional object of the invention is that of providing appropriate circuitry for indicating the velocity at which the moving club head impacts the golf ball with a result that by appropriate meter indication and for an assumed;

nub head velocity as it approaches the ball is so close to constant that the integrated value of charge over such a short time element provides substantially an approximate measure of the instantaneous velocity it is possible to translate the indication to one of actual club head impacting velocity. This will be explained more particularly in the discussion of Fig. 2, but suffice it to say at this point that on the control apparatus 21 a meter 25 may be included within the field of view of the golfer in accordance with the deflection of which there may be provided the desired indication. With proper meter calibration a translated value of ball travel distance is discernible. Such a meter may be reset by the control switch 121 following each swing motion.

In accordance with different club heads, such as a 2 iron, 5 iron and 7 iron or a 1 wood, 3 wood or 4 Wood, for instance, to impact the ball 11 an appropriate related scale on the meter may be read, it being apparent that the ball travel will be partly in accordance with the elevation or angle of tilt of the impacting club head.

Considering now one illustrative embodiment of circuitry by which the features exemplified schematically by the showing of Fig. 1 may be realized, reference may now be had to Fig. 2 of the drawings.

In the showing of Fig. 2 the control units shown constitute illustratively two of five assumed such units, it being supposed for purposes of illustration that the upper unit represents the first of a series and that the lower unit represents the third of a series. According to the foregoing assumption, the lower unit depicted by Fig. 2 may be considered, for instance, as arranged so that the phototube 17 thereof is located along the swing path taken by the golf club head so as to be approximately opposite the point at which the club head would stroke a real or simulated golf ball.

Considering now, for instance, the upper of the two circuits, generally marked A, and with it being understood that circuit B shown below it operates in substantially like fashion, it will be appreciated that tube operating voltage is supplied to the anode element 27 of the phototube 17 from a suitable voltage source (not shown) connected at the terminal point 29. The photoelectric cathode element 31 of the phototube 17 is preferably grounded at 33. This form of connection is one such that light falling upon the photocathode 31 produces a current flow through the phototube 17. Any current flowing through the phototube causes a voltage drop to occur across the resistor 35. The result of such a voltage drop is that the potential at the point 27 becomes negative with respect to that which would be maintained with the phototube in its darkened or unilluminated (cutoff) state so that the voltage of the source is effective at the point 37.

A suitable amplifier unit comprising the two halves of a tube, illustratively shown at 39, receives the phototube output. A suitable tube for this purpose may be one of the so-called 12AU7 type, or, in the alternative, two completely separate tubes may be employed. The grid or control electrode 41 of one of the tube sections receives the phototube output by the way of the connection made at the point 37 through the capacitor 43. Bias is obtained on the tube cathode by way of the resister 45. The resistor element 47 provides a suitable grid leak. The left half of the tube 39 is loaded by the output resistor 49 through which operating plate voltage from the source connected at 29 is supplied.

Output voltage from the left-hand half of the tube 39 controls the potential efiective at the grid or control electrode 51 of the right-hand half of the tube 39. Bias for this tube is supplied by the cathode resistor 55, with the resistor 57 providing the grid leak. Operating plate voltage is supplied by the source connected at 29 through the plate or load resistor 59. The output voltage from the right-hand half of the tube 39 is fed through the coupling condenser 61 to two separate paths of which one is to the control grid 63 of a control or triggering" tube 65, which, illustratively, may be one of the type known in the art as the 2D2l, which is a gaseous discharge tube of the so-called Thyratron type.

The triggering tube 65 has its screening electrode 67 connected to the cathode 69 directly. Operating voltage for the plate or anode 71 is provided from the source connected at 29 by way of the tube output resistor 73. A suitable operating bias on the tube 65 is obtained from a voltage source, indicated as the source 26 v. connected to terminal point 75 and to the tube grid 63 through resistor 77.

While the range indicating circuit, later to be discussed, is to be controlled by way of the voltage available on the conductor 79, constituting the second output path above mentioned, this discussion need not be entered into at this point, but it may be assumed here that the output of the tube 65 is fed through the coupling condenser 81 to the primary winding of a suitable transformer 83 in the secondary of which voltage amplification occurs. One end of each of the primary and secondary windings of the transformer 83 is grounded with the free end of the secondary winding being connected to a controlling electrode 85 of one of the illuminating tubes 23 which, as already mentioned, may be of the type known in the art as the SA309. This tube, when triggered, serves to discharge the charge stored in a suitable condenser 87 which is connected through the charging resistor 89 to a suitable source of voltage such as the source marked +700 v., for instance, shown connected at the terminal point 91. With operation of the tube 23 the condenser is discharged through the tube to flash it and so as to illuminate any object within range thereof.

Under the circumstances, it will be observed that if light is striking the phototube 17 the potential at the anode thereof which is available at the terminal 37 is reduced to a minimum with a result that current flow can be considered as interrupted in the left-hand half of the tube 39. At such a time current flow occurs through the righthand half of this tube and produces a voltage pulse eflective at the grid or control electrode 63 of the tube 65 which is of sufficient magnitude to reduce its potential to an extent to carry the tube operation to a cut-01f state because this voltage is available in addition to the bias voltage source connected at point 75. The result is that the potential available at the tube anode 71 is a maximum and flashing of the tube 23 cannot occur. If, however, the light directed into the phototube 17 should be interrupted the reverse conditions occur and because of the light interruption current flow in the phototube 17 is reduced and the potential available at the terminal point 37 rises to an extent sufiicient to cause conduction through the left-hand half of tube 39 so that a consequent cut-off of current flow through the right-hand half of this tube occurs. For this condition of operation the potential available to control the triggering of the grid 63 of the tube 65 rises to an extent sufficient to overcome the bias available at the point 75 and starts conduc tion within the tube 65 and a resultant drop in potential at the anode end of the load resistor 73. This change in conduction within the tube 65 causes a pulse to be transferred through the transformer-83 to the controlling element 85 of the light source 23 to an extent such that the condenser 87- can discharge through the tube and bring about a state of illumination therein. Under these conditions it will be appreciated that the potential available on the conductor 79, with interruption or decrease in the light available at the phototube 17, becomes more positive than is the case with light effective at the phototube 17.

The conditions of operation in the lower section, marked B, of the drawing comprising the lower phototube 17 and other components identified by numerals corresponding to those of the upper portion A of the 75 circuit with the addition of primes where possible bring tubes 'and the triggeringeireuitsjaetiyated th reby above, out-linedtor the-circuits -niarked Since, however; thevarious p'lfototuties are= arranged' in" t a'pp'eats'tohe anoptically' stationary position; Th

"fifth photo- "a trial the second; 'fouith and fifth"light souhces liave heti illustrated; the operation would alsena e-aeen like fli'at Should the as-suineeseene, fbiiffth" such :away that-"the-light' reaching thetn is eclipsed in an orderly sequence as'the club head is moved-it Wilib appreciated that the lights ilt are also 'flash'eti in like sequence: Uhder th'se'condition'sj the illumination: ff'cinik the 'lam'ps z d flashing sequence isfsufficient 'tb 'i Hitm'i- 1 1 1 new Brilliantly the clubfhead servihg as a" light interrupfi',

in'gmedium 'and effectively held itfor an instant in v'tilia't provide then an indication to the golfer at-the precise time of the-swing. of the exact position ofthegolf club;

head aldng'ithe swing path, both'with respect to the'line't ofclhbhead niotio'n as itis ielated to an optimum swing;

path andlas t'o the'prec'is'eposition of the'fcl'ub'h'ead rel-' ative t'o-th'eball; real or simulated, to beitnpacte'd a's-a fresulf-ofi the swingi g r l 7 t Ashas' been suggested in'the portion bf this' de'sc'riptionwhichhaspreceded -thisexlilan'ation of the clu'b'diafd illuminationcontrol; another important feature of'the" "invention i's that of determining. the velocity cf' impact ofthe-club head tiptin the ball soas t o 'filrh i'sh' a basis" fi'onfwhicn the' distaneeiwhich the ball would move for- V ahyepartictilar-impactingclubhead speed may-:be deiivedi 7 To this end it is-in'ipo'rtaht that the observation of-club' head velocity be made-at substantially the precisepoiht ofihall irnpactbec'ause it is at that point in-the swing wheretheclub "head strikes theball tocontpress it" and then; as a resultiof arapid-expansion ot the'cdnipr'essed elastic body 'being eflective against the'm'ovingclub-head,-

such 'as'to insure an accurate representation-oftlfe exact" velocity; this inv'en'tion isso' constituted that zit-the per-1' tio n" of the" golf swing when the club head-' motibni-is V almost-precisely;uniform; that 'is at tliedhstahfoiifiirigizit ahd within avery" short" instaintpriori'to a'ctual? im aee 7 it'fis'possihle-almos'tprecisely to"detern'fine ith'ef may veimit erme clubhezdbybtitaifingan-integrated valhe indicativeof Citih head speed integrated 'Between 'tw'o' lii'nitihg' points. 1 Onefo'f them" may bea point 'ofknewn':

distance-along the pathjtaken "by the club head 'i'h-its nseeeswing toward the ba ll t'o vbeimpa'cte'd' ahdthe othen may: he "a point substantially coinciding" withnfiefactjual" Tbprodhcea'n indication ofsuch character, the" ti-iggering potentials available upon theconducto'rs 79151116" 75f are initiatedrespectively at' a point alchown distance aheadiof the bail position; :and at the'ball' position it can be appreciatedthatameasurement can be'deriyedthrough' V a an appropriate indicating circuit which will-indicate what ]:fa's h'appenedimthe interval of time between which'the:

moving-g c'l'ubjhead eclipses-the light; striking- 'thdpfi'dtotube 17' which'conti ols th'e ttigg'ering voltageefiective upon thecon'd'uctor ,79'and thatcphototubfe'whichcontrols the triggering voltage available 'inconductor 79; Since? the-voltagepulsesj effective on the'c'onducto'rs 79*an'd' 79 are of'p'osi'tive polarityt'as herein explained) with -inti'e rruption off-the light upon the-related 'ph'ototube 11, it war he appreciated that'at all other times the polarityulses'is negative, Consequently, at the'instant' the 211 first cff thei-phtotfihes 1-7-jis 'i1i'terrupte the pew a1 vailaal'an "n the donztuetofw;iand whr is ajgipiied te the eon t electrons-93 ef-flre-tnbe 95, is safttciem lyrpositive tcx renuce conduction: therettrr'ongh.- wittx'v-nlbe s -i iconduetingg the" voltage aeross -ttie 566i? esasgee'e a a denselee 7; wiiiithasten 'tan ne av tyfireiative thereto, the tube y-s wil l hold ope'tation established until eut ofiiby the r late. VoItageIonredilction therebf to a negtigibt tube-:ttien acts'iir snch a'wayhs to'plaeetheyolt ge he 105,;Where; the cathode resistor-.3103 --ti:oniiet5ts ito'the tube;

- tionn-iwill hold until the tube- 95i isq'ren'derecl non=conducit-- ing by; a:controt=0f:=the' na-ttireialready specified. I

when conductivity: within the tube- 95 places the' yolta gei built up'acr ossthe condenser'97 sozthat it'is'efiective atg the fpbint";:such piotential is sufiicientto provide the' plateipbtentialnecessary. to 'cause a current tto fl'ow through the left-handhalfjqfztube 7109. As: shown by";

etfectively; to provide a cdi'ode type of connecti0n,,;with: the connected terminals. for. ther tube grid and lplate con' nected to the-point 105 which provides the positiye-anm v0lta geonthe-lefttendioftheitube; The'vo'l'tageiapplietfi to-Vanodegrid elements of th'is' tuberhalf'i'elative to 'th t c'athcde is sufi'icientto 'cause;this:tnbe half to pass' I currentwhich flows thi ough this tubexhalf and theetub cathode resistor 117'in the directionto char-ge theycon denser 11-9, Theacu'rrent fiowfs inza: direction such tha akcharge Builds up'within; the condenserin a: direetionif whicli 'make's its upper plate posifive' relative to ground:

the con ii a 33; .v .;T hecondenser charging continues:

ductiontpe iodoftube-95. I a a a a I When a' pos'itivezpulse appears 7 upouhthe 'conductorflwl which is ofia sufficient magnitude to overcome the biasingi' k voltage-applied td the' g r idl29of the'tube 131f1'om1thti source connected with its-negative terminal turned ward'tlie terminaLpoint 75', .it will be observed wthat tube 131 immediately 'fires or conductsrrBy4'iteason..ot the connection :of': the'tubeaanode 133 to: the positively charged termihal oi: the condenser '97 it vtirill'.= .'l:1e:- appre'ei1- ated th'tnhe; cendensen'is short-f eir'cuited "by a path"v malbias-isadequate tor'cu t difg theatub'esiand':fetumittienz i l te a :state bf: substantiallyinfifiiteqilate nesistance. The: cohiienser '97-atli en i's -ifecharged throughathe resistdr 19 1i so' the system isia gainaready to zopei'ate-v' :1 .7 a

' WhenE theIcondiIiiSnsmfioperation-aszabove outlinedia'rez (showinas"+200 -v.-') conneeted at thezterminal point '9 9 m maintained Knit -with -thertchargingi'of the-' condenserillti throiigh the leftihalflof theztub'e tflfiait willi baapparenti V .ttibtti theb show:.preventqther chargaom e? condnser lflifromr fioyiing tb ground "through :the gree j sisters 17 ande103i by reas o'nmf the factthatithiegposis" "7'5 tisie ietentiatiiemaintained aethepointzlosa .The yolt'agea V up across the condenser ettectiyelyiaefoss tlie resist 103} The resiilt-i's that the'potentialiefiective rat the pdint i cathode 107,.wi1I be maintained"at'z'suhstantiallyFconstani i value during conductivityawithinxthetithe 9'5. count-1i -Under-the circumstances; it will be -appreciated that? V -2' of; the drawingsythe -igrid 1 11 ahdiplatellli bfthe; liefthalf; of the tube 1 109ia're: connected .togetliensoas;

V minimuniil'esistancefwith thegresulfi that fth'e'cendenseifl 9? completely discharges almost instantly; 7 The; com iTI denser-discharge thenireduceeithe platepotential; onathe illna veryshort space ofitiriie iixshally a'lfewseconds; '5 65 usingiipreferred-zoircuit patametersrhfthe condenser: is charged up Itoisuhstahtially thehva'lue fof the''25mn'eef which is produced across the condenser 119 in its charging is read on the applied vacuum tube volt meter. The volt meter is a generally familiar component and, as shown, includes the right-hand half of the tube 109 and embodies the biasing source 123 connected to the grid 125 with its negative terminal turned thereto and the positive terminal turned toward the junction of the cathode resistor 117 and the condenser 119. The volt meter also includes the plate current meter 127 and the plate current adjustment resistor 128 so that in accordance with the charging of the condenser 119 an indication is provided on the meter 127. The magnitude of the charge built up is a function of the time elapsed between that instant when tube 95 is initially caused to conduct and the time instant when the tube 131 conducts to discharge the condenser 97 and thus cut off both tube 95 and the tube 131. A switch 121, connected across the condenser 119 to short circuit it to ground, may be closed to restore the vacuum tube volt meter to a condition of zero reading after the circuit has once functioned.

From what has been stated above, it becomes apparent that the voltage developed at the point 105 will hold at a substantially constant value from the time coinciding with that upon which the gaseous tube 95 is triggered until such time as the second control gaseous discharge tube 131 is triggered. During the time period that the voltage is available at the point 105, it has also been pointed out that the left-hand section of the tube 109, which is connected to function as a diode, operates to charge the condenser 119. The value of charge acquired by condenser 119 will remain substantially constant since (with the switch 121 open) the condenser has no discharge path to ground, although as a practical matter the leakage resistance through the condenser and associated components will slowly cause the condenser to discharge, but this leakage is very small if high quality components are used. It is the voltage which is built up upon the condenser 119 that controls the reading obtained upon the vacuum tube volt meter. The closing of the switch 121 removes the charge by short circuiting the condenser to ground.

Considering these conditions, the graphical representations in Figs. 3A and 3B are presented to depict, in a measure, the conditions which obtain to measure the velocity at which the golf club head will impact the ball. Considering first Fig. 3A, there is represented the conditions which obtain with a relatively rapid swing of the golf club toward the ball. With such a swing the velocity of the club head as it strikes the ball, is very high, meaning, of course, a greater travel or flight distance for the impacted ball. The conditions depicted by the showing of Fig. 3A are such that time is assumed to be read from left to right. The upper curve is an indication of the constant pulse available on the conductor 79 to trigger the tube 95 to an operative state. This pulse develops at the time the club head eclipses the first light beam used to provide the measured indications. The operative or conducting state of tube 95 is maintained until a triggering pulse appears on the conductor 79 to trigger the second tube 131 to an operative state and immediately discharge the condenser 97. The pulse on the conductor 79 is represented by the second curve. It is spaced in time from the pulse in conductor 79 by that time elapsing between the club head eclipsing the first light beam and eclipsing the light beam controlling the development of the pulse on conductor 79 The third curve down represents the voltage available at the point 105 to serve as the anode voltage of the diode section of the tube 109 to charge the condenser 119. The voltage to which condenser 119 charges is represented in the lowermost curve. As can be observed from the curve the time interval between the occurrence of a con trol pulse on the conductor 79 and the occurrence of a similar control pulse on the conductor 79 determines the time period during which the condenser charging occurs.

Consequently, the voltage acquired becomes indicative of the time elapsing between the club head entering one light control path and the time when it enters the last of the light control light beam paths. The more rapid the club head is moved the shorter will be the elapsed time between the occurrence of the pulses on the conductors 79 and 79 and, consequently, the less will be the charge built up upon the condenser 119. This means that the indicator reading on the meter 127 if maintained in a direct proportion to the charge may be assumed to represent the voltage on the condenser 119 and suitable calibration will then provide direct reading of ball flight distance and other related facts.

Considering now Fig. 33, similar conditions are represented but it has been assumed that the club head swing is slow so that a greater elapsed time is depicted between the occurrence of the control pulse on the conductor 79 and the control pulse on the conductor 79 than for Fig. 3A. As is evident, this means that the voltage for the diode section of the tube 109 which becomes available at the point is maintained for a greater period of time with the result that the condenser 119 can charge to a greater extent. This has been indicated by the lowermost curve of Fig. 3B which represents the voltage across the condenser at a value greater than that depicted for the curve of Fig. 3A.

With this showing, it becomes evident that it is possible, in accordance with the magnitude of the charge acquired by the condenser element 119 to determine not only the velocity at which the club head is moving at the instant of impact, but also through appropriate instrument calibrations the distance to which the golf ball would travel for any given condition of wind, temperature, humidity, and even wetness of the grass upon which the golf ball would come to rest.

It is, of course, apparent that numerous modifications may be made in the foregoing invention, included among which may be the manner of imaging the light sources upon the phototubes, the object toward which the golf club is adapted to be swung, the calibration of the meters to indicate the end results, and so on. These are, of course, well within the scope of the invention as herein set forth.

Having thus described the invention, what is claimed 1. A golf trainer for directly observing the swing path of a club head at spaced points in its movement toward contacting a ball which comprises a plurality of stroboscopic light sources arranged in sequence substantially adjacent and parallel to the swing path adapted to be taken by the club head, a normally illuminated light sensitive device connected with each stroboscopic light source said devices being also located at selected spaced points adjacent to the swing path on one side thereof and adapted to initiate an illumination of said source with an abrupt change in the instantaneous current flow in the light sensitive device, the sources of illumination for normally illuminating the light-sensitive devices being on the opposite side of the swing path from the light-sensitive devices, whereby the light paths are interrupted in sequence with movement of the golf club along said path whereby an individual swinging a golf club along the path is able to observe coincidentally with the swing and under the direct control of the swing the precise path of club head movement relative to the optimum swing path.

2. A golf trainer for directly observing the swing path of a club head at spaced points in its movement toward contacting a ball which comprises a plurality of stroboscopic light sources arranged in sequence substantially adjacent and parallel to the swing path adapted to be taken by the club head, a normally illuminated light sensitive device connected with each stroboscopic light source said devices being also located at selected spacedpoints adjacent to the swing path on one side thereof and adapted to initiate .an illumination of said source with an whereby the velocity of impact of the fixed object by contact of the moving body therewith is measured.

8. In a golf trainer device, the combination comprising a plurality of stroboscopic means for illuminating selected substantially adjacent regions of a path along which the head of a golf club is adapted to be moved to strike a golf ball, a plurality of alined light-sensitive elements positioned approximately adjacent and parallel to the optimum path of motion of the club head and located in the region wherein the club head is adapted to impact the ball, means for continuously illuminating the lightsensitive elements from the opposite side of the path for initiating and maintaining normally a current flow of generally constant value through the light-sensitive elements, said current flow being adapted to be interrupted in sequence from one light-sensitive element to another in coincidence with the motion of a golf club head along a path between the light-sensitive elements and the illuminating means, and means responsive to an interruption in current flow through the light-sensitive elements due to the club head producing an interruption of light to initiate the operation of the several stroboscopic illuminating means in sequence and in coincidence with the golf club head motion, whereby along such illuminated path a rapidly moving golf club head may be visually observed as if arrested in its motion at progressive changing points in the region of impact and in accordance with its rate of motion therealong.

9. In a golf trainer device, the combination comprising a plurality of stroboscopic means arranged adjacent to a swing path of a golf club for illuminating selected regions thereof at a sequence of points adjacent to which the head of a golf club is adapted to be moved to strike a golf ball, a like plurality of alined and normally illuminated light-sensitive elements positioned approximately adjacent to and parallel to the optimum path of motion of the club head and located in the region wherein the club head is adapted to impact'the ball, means for initiating and maintaining normally a current flow of generally constant value through each of the light-sensitive elements, said current flow being adapted to be progressively interrupted in sequence from one light-sensitive element to the other in coincidence with the motion of a golf club head to impact a ball eclipsing the illuminating light to said light-sensitive elements, means responsive to an interruption in the current flow through each of the light sensitive elements to initiate the operation of a therewith related and connected stroboscopic illuminating means in coincidence with the timing of the golf club head motion, whereby along such illuminated path a rapidly moving golf club head may be visually observed as if arrested in its motion at progressively changing points in the region of impact, and means responsive at the start and termination of club movement Within the impact region to measure the club head velocity.

References Cited in the file of this patent UNITED STATES PATENTS 2,174,804 Neville Oct. 3, 1939 2,223,849 Fogler et a1. Dec. 3, 1940 2,283,277 Modine May 19, 1942 2,571,974 Walker Oct. 16, 1951 OTHER REFERENCES Flash! Seeing the Unseen by Ultra High Speed Photography, Edgerton and Killian, Jr., 1939, Hale, Cushman & Flint, Boston. 

